just finnished putting bike back together, run it up the road and my old problem is still here. runs fine on stand and revs freely. when under load eg im riding it, it pulls fine till about 8000 rpm then struggles to rev / pull, sounds like a bag of poo until abot 10500/ 11000 rpm then goes like hot snot. have had the carbs off, and cleaned numerous times, was wondering if it might be the magic box. any ideas or sugestions would be very much appreciated. thanks nick.